1. Field of the Invention
The present invention pertains to a whipstock for oil and gas wells, particularly adapted for insertion into a well through a tubing string and including setting mechanism for positioning the whipstock guide surface after placement of the whipstock at a predetermined depth.
2. Background
The increased use of coilable tubing for performing well operations including "sidetracking" or drilling deviated wells from an existing wellbore has increased the need for a whipstock which may be inserted through a tubing string and then actuated to a set position upon exiting the lower end of the tubing string so that casing milling tools and drilling tools may be properly guided.
Improvements in drilling and coring operations and improvements in whipstocks for performing operations to drill and core with coiled tubing through existing well tubing strings are disclosed in U.S. patent application Ser. Nos. 07/752,704 and 07/752,705, both filed in the U.S. Pat. and Trademark Office on Aug. 30, 1991 and both assigned to the assignee of the present invention. Although application Ser. No. 07/752,705 discloses and claims a whipstock which may be inserted through a tubing string and set to provide proper orientation of the tool guide surface after exiting the lower end of the tubing string, the present invention provides further improvements in whipstocks which are particularly advantageously used for the methods described in the above-referenced patent applications as well as other applications where whipstocks may be required.